نتایج جستجو برای: trans and vinyl
تعداد نتایج: 16841581 فیلتر نتایج به سال:
This article is the first comprehensive review on the study and use of vinyl ester monomers in reversible addition fragmentation chain transfer (RAFT) polymerization. It covers all the synthetic aspects associated with the definition of precision polymers comprising poly(vinyl ester) building blocks, such as the choice of RAFT agent and reaction conditions in order to progress from simple to co...
Polyaniline (PANI) nanocomposite has been successfully prepared in aqueousmedia by the chemical polymerization of aniline with ammonium peroxydisulphateas an initiator in the presence of a steric stabilizer such as sodium dodecylbenzenesulfonate(DBSNa), Poly(vinyl pyrrolidone) (PVP), poly(vinyl alcohol)(PVA), poly(ethylene glycol) (PEG) and hydroxypropylcellulose (HPC). Thechemical structure, m...
background: all-trans retinol is a biological antioxidantscavenging the ros in the cell culture. objectives: this studywas conducted to investigate the effect of all-trans retinol infertilization and culture medium on mouse embryo's developmentalcompetence. methods: this study was designed into twoexperiments. in the first experiment, in vitro mature oocytes wereco-cultured with sperm in fertil...
Vinyl chloride is a manufactured substance that is used to make polyvinyl chloride (PVC) plastic products, such as pipes, wire coatings, packaging materials, and cigarette filters. Because vinyl chloride usually exists in a gaseous state, the most common way of taking vinyl chloride into the human body is inhalation. People whowork at or near a facility thatmanufactures vinyl chloride and PVC p...
Homoallenic alcohols are prepared from propargyl vinyl ethers using a trinuclear gold(I)-oxo complex, [(Ph3PAu)3O]BF4, as a catalyst for propargyl Claisen rearrangement at room temperature. The gold(I)-catalyzed reaction is effective for a diverse collection of propargyl vinyl ethers, including substrates containing aryl and alkyl groups at the propargylic position, and hydrogen, aryl, and alky...
The purpose of this research was to develop an applicable sampling and analytical method to determine airborne 4-vinyl-1-cyclohexene concentrations which are usually found in the atmosphere of polybutadiene factories. A solid sorbent tube, containing two sections (100 mg in the front and 50 mg in the back) of activated coconut-shell charcoal was chosen for sampling 4-vinyl-1-cyclohexene vapor. ...
In this study silver/poly vinyl alcohol (PVA) and silver/poly vinyl pyrrolidone (PVP) Nanocomposites were prepared via reduction of silver salt by employing DMF (N, N`- dimethyl formamide) as a reducing agent. Effects of protective agents such as PVA and PVP were also described here. We show that the acidic pH of PVP solution also affects the interaction between protective agents and silver nan...
The chemical structural differences distinguishing chlorophylls in oxygenic photosynthetic organisms are either formyl substitution (chlorophyll b, d, and f) or the degree of unsaturation (8-vinyl chlorophyll a and b) of a side chain of the macrocycle compared with chlorophyll a. We conducted an investigation of the conversion of vinyl to formyl groups among naturally occurring chlorophylls. We...
Recent results in the chemistry of disubstituted carbenium ions (vinyl cations and phenyl cations) are described separately under three different sections: From kinetic and solvolytic data of several 1—cyclobutenyl nonaflates, the intermediacy of a non-classical vinyl cation, namely the 1-cyclobutenyl cation 2 is established. Cycloaddition reactions of solvolytically generated vinyl cations wit...
Consideration of needs for public health interventions and new research requires comparative assessments of the health benefits that are likely to result from alternative uses of limited regulatory and technical resources. This paper briefly examines regulatory and research priorities in the light of recent information on the carcinogenic hazards of vinyl chloride and alkyl and vinyl halides re...
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